love2d.love/src/common/b64.cpp

/**
* Copyright (c) 2006-2011 LOVE Development Team
* 
* This software is provided 'as-is', without any express or implied
* warranty.  In no event will the authors be held liable for any damages
* arising from the use of this software.
* 
* Permission is granted to anyone to use this software for any purpose,
* including commercial applications, and to alter it and redistribute it
* freely, subject to the following restrictions:
* 
* 1. The origin of this software must not be misrepresented; you must not
*    claim that you wrote the original software. If you use this software
*    in a product, an acknowledgment in the product documentation would be
*    appreciated but is not required.
* 2. Altered source versions must be plainly marked as such, and must not be
*    misrepresented as being the original software.
* 3. This notice may not be removed or altered from any source distribution.
**/

#include "b64.h"

namespace love
{
	static const char cd64[]="|$$$}rstuvwxyz{$$$$$$$>?@ABCDEFGHIJKLMNOPQRSTUVW$$$$$$XYZ[\\]^_`abcdefghijklmnopq";

	void b64_decode_block(char in[4], char out[3])
	{   
		out[0] = (char)(in[0] << 2 | in[1] >> 4);
		out[1] = (char)(in[1] << 4 | in[2] >> 2);
		out[2] = (char)(((in[2] << 6) & 0xc0) | in[3]);
	}

	char * b64_decode(const char * src, int slen, int & size)
	{
		size = (slen / 4) * 3;

		char * dst = new char[size];
		char * d = dst;

		char in[4], out[3], v;
		int i, len, pos = 0;

		while(pos <= slen)
		{
			for(len = 0, i = 0; i < 4 && pos <= slen; i++ )
			{
				v = 0;

				while(pos <= slen && v == 0 )
				{
					v = src[pos++];
					v = (char)((v < 43 || v > 122) ? 0 : cd64[v - 43]);
					if(v)
						v = (char)((v == '$') ? 0 : v - 61);
				}

				if(pos <= slen)
				{
					len++;
					if(v)
						in[i] = (char)(v - 1);
				}
				else
					in[i] = 0;
			}

			if(len) {
				b64_decode_block(in, out);
				for(i = 0; i < len - 1; i++)
					*(d++) = out[i];
			}
		}

		return dst;
	}
} // love